Single-stream recycling, where households toss paper, plastic, glass, and metal into one bin, is convenient for residents and difficult for the facilities that then have to separate it all back out again. Materials recovery facilities do that separation using a mix of machinery, magnets, optical scanners, and, still, a line of people picking out what the machines miss. Elvira Sandoval has worked a sorting line at one such facility for six years. We spoke during her lunch break, in a break room she notes is the only quiet room in the building.
What does the machine actually get wrong that a person has to catch?
Plastic bags, mostly, and anything tangled together. The optical sorters read a material by shining light on it and reading how it reflects, which works well for a single clean bottle moving past on its own. It works badly for a plastic bag wrapped around a cereal box, because the sensor might read the bag, might read the box, might read neither correctly. Bags are actually the worst thing people put in a recycling bin, not because bags can’t be recycled somewhere, but because they jam the machinery here specifically, wrapping around rotating shafts until someone has to shut the line down and cut them free by hand.
How fast does the line move?
Faster than people picture. Material comes past on the belt in front of me at a pace where I have maybe one, two seconds to identify an item, decide if it belongs in what I’m pulling, and pull it, before it’s gone past my station. You develop a kind of pattern recognition that stops being conscious. I don’t think “is that a yogurt cup,” I just see it and my hand is already moving.
What’s the most common thing people get wrong about what belongs in the bin?
Greasy pizza boxes. People know cardboard is recyclable, so they assume the box is fine, but grease contaminates the paper fibers and a load of pulp with too much oil in it can ruin an entire batch at the paper mill we sell to, not just the one box. Same idea with a jar that still has peanut butter in it. If I can still see food residue on something at my station, it’s not going where the person who threw it away intended, it’s going to the residual pile, which means it’s going to a landfill after all.
Is there anything people throw away as trash that actually shouldn’t be?
Scrap metal, small stuff especially. A broken pair of scissors, an old doorknob, those have real value on the metal side of this business and people bin them as garbage constantly because they don’t think of them as “recycling” the way they think of a soda can. Meanwhile the soda can, which people are very good about recycling, is honestly one of the easiest, most valuable things we process. It’s the stuff that doesn’t look like recycling that gets missed both directions, thrown away when it shouldn’t be, and put in the bin when it can’t be sorted.
After six years, has it changed how you handle your own trash at home?
Completely. I rinse everything now, not spotless, just enough that there’s no food left to contaminate anything near it. I don’t bag my recycling in a plastic bag anymore, I learned that lesson from watching what bags do to this line. And I’ve stopped assuming a recycling symbol on something means it’s actually recyclable here. There are seven different numbered categories of plastic and this facility can only actually process two of them profitably. The symbol tells you what the plastic is made of. It doesn’t tell you anyone wants it.